Herbicides are applied to crops and to the soil in which crops are to be grown to prevent or control the growth of weeds. When applied postemergence to crops, herbicides are often applied using conventional pressure broadcast spray methods. Commonly used commercial herbicides which may be broadcast sprayed are listed in Table I:
TABLE I ______________________________________ Herbicide Source Active Ingred. Class ______________________________________ Assure II .TM. Du Pont quizalofop grass herbicide Basagran .TM. BASF sodium salt of bentazon broadleaf herbicide Blazer .TM. BASF sodium salt of acifluorfen broadleaf herbicide Classic .TM. Du Pont chlorimuron ethyl broadleaf herbicide Cobra .TM. Valent Co. lactofen broadleaf herbicide Fusion .TM. Zeneca fluazifop-p-butyl and grass fenoxaprop-ethyl herbicide Galaxy .TM. BASF sodium salts of bentazon broadleaf and acifluorfen herbicide Pinnacle .TM. Du Pont methyl 3- broadleaf [[[.sub.[4-methoxy-6-methyl-1,3,5- herbicide .sub.triazin-2-yl] amino]carbonyl] amino]sulfonyl]2- thiophenecarboxylate Poast BASF 2-[1-.sub.ethoxyimon] butyl]-5-[2- grass Plus .TM. .sub.[ethylthio] propyl]-3-hydroxy- herbicide 2-cyclohexene-1-one Pursuit .TM. American ammonium salt of grass/ Cyanamid imazethapyre broadleaf herbicide ______________________________________
Further data about the above-listed herbicides are available in the following U.S. patents and U.S. Environmental Protection Agency registrations: Assure II.TM.--U.S. Pat. No. 4,629,493; Basagran.TM.--U.S. Pat. No. Re. 31,455 and E.P.A. Reg. No. 7969-45; Blazer.TM.--E.P.A. Reg. No. 7969-79; Classic.TM.--U.S. Pat. Nos. 4,394,506 and 4,547,215; Cobra.TM.--E.P.A. Reg. 59639-34; Fusion.TM.--E.P.A. Reg. No. 10182-343; Galaxy.TM.--E.P.A. Reg. No. 7969-77; Pinnacle.TM.--U.S. Pat. No. 4,481,029; Poast Plus.TM.--E.P.A. Reg. No. 7969-88; and Pursuit.TM.--E.P.A. Reg. No. 241-310.
Application of postemergence herbicides can, however, have a deleterious effect not only on undesirable weeds but also on the primary crop. For example, when herbicides are broadcast, the leaves of the primary crop can burn, shrivel or discolor. This damage can be extensive, sometimes damaging over 40% of the leaves of the plants of the crop. In addition to giving the crops a poor cosmetic appearance, plant growth can be stunted. Even when plant growth is not permanently stunted and subsequent new leaf growth replaces the injured leaves and restores the plants to optimum growth rates, during the time period the plant leaves are damaged, transpiration efficiency can be effected, plants can be weakened and growth phases can be retarded. These problems have not heretofore been fully addressed.
Fertilizers and plant additives are also commonly applied to the soil in which crops are to be grown and to the soil after plants have emerged from the soil. For example, aqueous ammoniacal ionic solutions of alkanoates having from two to six carbon atoms have proven effective in stimulating plant growth in corn, soybeans, wheat and other crops. Metal ammonium alkanoates have proven especially effective, with agriculturally acceptable metals selected from the group consisting of boron, calcium, copper, iron, magnesium, manganese, molybdenum, potassium, sodium and zinc preferred.
More particularly, U.S. Pat. No. 4,352,688 for "Nitrogen Fertilizers" to Ott teaches that low molecular weight alkanoic acids and alkanoate anions thereof, particularly acetic acid and acetate ions, effectively promote plant growth and yield by enhancing the ability of nitrogen fertilizers. U.S. Pat. No. 3,909,229 for "Plant Nutrients" to Ott teaches aqueous ammoniacal ionic solutions of zinc carboxylates, for example zinc acetate in combination with ammonia, as effective fertilizers. U.S. Pat. No. 3,997,319 for "Fertilizing Method" to Ott teaches the application of substantially anhydrous liquid ammonia containing an ionic solution of a zinc carboxylate to soil below the surface of the soil, in order to supply zinc and nitrogen to plants growing in the soil.
Substantially anhydrous liquid ammonia is typically injected below the soil surface, under pressure. Anhydrous liquid ammonia is typically applied in fall--after the end of the growing season, in early spring--prior to planting, or in late spring--post-emergence, i.e. after a crop has germinated and leafed out. While ammonium nitrogen is readily assimilated by plants and thus liquid anhydrous ammonia is a preferred fertilizer, the aforementioned method is avoid when wet soil or windy weather conditions prevail. When weather conditions are unsuitable, growers may skip scheduled early spring, late spring or fall applications of anhydrous liquid ammonia. When this occurs, crop yields may be reduced. Moreover, for any aqueous ammoniacal ionic solutions of metal alkanoates or other crop additives which were to be applied with anhydrous ammonia, a missed application of anhydrous ammonia also results in a missed application of the crop additive.
In some cases the liquid fertilizer which functions as a carrier for the aqueous ionic solution of metal alkanoates plant additive solution may be broadcast to the soil in a field before plants have emerged. Application of the aqueous ionic solutions of metal alkanoates in such cases is typically tied to a scheduled application of the liquid fertilizer. However, fertilizers are generally not broadcast sprayed after plants have emerged because of the fertilizers tend to cause substantial damage to the crops by burning the leaves. Instead, fertilizers added postemergence are generally applied directly to the soil using drip, injection and side dressing methods.
One agricultural crop additive of the class of ammoniacal ionic solutions of zinc carboxylates described herein is commercially available under the ACA.TM. Concentrate 15-0-0 trade mark from Platte Chemical Company of Fremont, Nebr. ACA.TM. Concentrate 15-0-0 is currently available as a liquid containing 15% by weight ammoniacal nitrogen and 17% by weight zinc. ACA.TM. concentrate 15-0-0 is typically applied at a rate of 1/3 pint to 2/3 pint per acre. It is the application of the solution at such low rates which is generally understood to require application of the alkanoate in conjunction with an anhydrous ammonia, water or nitrogen fertilizer carrier to the soil by preemergent broadcast spraying, pre- or postemergent injection means, or post emergent drip means or side dressing.
It is against this background that the significant improvements and advancements of the present invention have taken place.